Multicell machine operating as a combination pressure-vacuum generator



Aug. 10, 1965 BECKER 3,199,771

MULTICELL MACHINE OPERATING AS A COMBINATION PRESSURE-VACUUM GENERATOR Filed 001'.- 16, 1962 United States Patent 3,199,771 MULTI ELL MACHHNE @PERATING AS A BENATEGN ERESS l-E-VACUUET GENERATQR Qtto Becker, vi uppertaldiarinen, and Gunter .leschke, Wuppertaldionsdori, Germany, assignors to Gebr. llecirer ambit, Wuppertal-Earmen, Germany, a firm Filed 6st. 16, 1962, Ser. No. 23ll5ll8 Claims priority, application Germany, Oct. 19, 1961,

4 @lalrns. (ill. 239-47) Combination pressure-vacuum generators are welllinown which are desi ned for the generation of a volume of compressed air as large as possible in the pressure chamber of the machine and with any desired vacuum in the suction chamber. For this purpose the cylinder is provided with a secondary suction adsorption arrangement through which after termination or" the suction process atmospheric air will enter the vacuum chamber, v "rich then will be compressed and delivered to the compressedair extraction place. The secondary suction arrangemerhowever, necessitates a shortening of the suction slot, for at least part of the chamber between the secondary suction adsorption arrangement and the controlling connecting edge or" the suction chamber is required therefor. this involves the disadvantage that because of the smaller suction chamber the volume delivered during the primary suction process is smaller than in standard vacuum pumps. Because in most cases only the primary suction adsorption is used for the working capac y the operating speed will be reduced owing to the smaller volume. Though the evacuated chamber will be filled again with atmospheric air, part or" the air entering is ejected by the secondary suction adsorption arrangement, for the cubic contents of the filled chamber will be eauced in case of rotation of the piston drum. The result thereof will be a reduction of the compressed air volume.

Another disadvantage lies in the fact that on entering of the atni spheric air through the secondary suction adsorption arrangement at a corresponc 1g pressure below atmospheric pressure in the suction adsorption char. ber of the primary suction adsorption there will take place a sudden increase or" pressure in the relevant chamber opposite the adjoining chamber. The sliding pistons are, therefore, subjected to a transverse force opposite to the direction of rotation of the piston drum which, especially in the case of light plastic slide pistons, will result in that the centrifugal force will no longer be able to press the sliding pistons out of the slots, so that they cannot abut upon the inside wall of the cylinder. Sealing of the chambers with respect to each other no longer takes place, and there will now be an ovenlow of air from the chamber, which is in connection with the secondary suction adsorption arrangement, into the suction chamber of the primary suction adsorption. The result is a drop of the vacuum.

It is an object of this invention to eliminate these shortcorninr by sirnple and economical means.

The invention provides a multicell machine operating as a combination pressure-vacuum generator, which cornprises in combination a cylinder, a piston drum arranged eccentrically in said cylinder so as to leave a substantially crescent-shaped working space connected with suction and pressure chambers, respectively, s ding pistons traversing independently or" each other in racial or tangential slots in the piston drum and subdividing the working space into chambers, the inside wall of said cylinder being curved in a section disposed within the vertex of said working space in accordance with a circular are curved concentrically to the s of rotation of said piston drum, while each end of said section is connected to a portion with the same tangents at the connection joints but wa ll ice with different radii of curvature, the centers of these circles being apart on a straig rt line which extends normal to the vertical central plane of said cylinder, and the free ends of said wall portions being joined by a connection piece curved according to a circle whose center is on a straight line extending in the vertical central plane of said cylinler. V

A preferred embodiment of the invention will now be descibed by way of example and with reference to the accompanying drawing, which is a cross-sectional View of a multicell machine according to the invention.

The drawing shows a multicell machine 1 comprising a housing 2 with a cylinder 3. The cylinder 3 is provided with an eccentrically arranged piston drum 4 so that the piston drum 4 contacts the inside wall 5 of the cylinder 3 at the running seal between a suction chamber 19 and a pressure chamber ill, the necessary tolerance being considered. In radial or tangential slots 6 in the piston drum 4 there are sliding pistons 7 slidable transversely to the direction of the longitudinal axis of the piston drum and pressed against the inside wall 5 of the cylinder 3 through centrifugal force. The ends of the cylinder 3 are closed by covers (not shown) which support the bearings of the piston drum Owing to the eccentric mounting of the piston drum 4 in the cylinder there exists a substantially crescent-shaped working space 8 which is subdivided into chambers h by the sliding pistons In the preferred embodiment eight sliding pistons '7 forming eight angles each of 45 are provided. The running seal between the inside wall 5 of the cylinder 3 and the piston drum 4 is the separation between the suction chamber it? and the pressure chamber 31.

As shown in the drawing, the inside Wall 5 of the cylinder 3 is not circular. The inside wall 5 of the cylinder 3 in section A extends in an arc of a circle concentric to the axis of rotation of the piston drum 4. The wall portions of the cylinder 3 adjoining both sides of section A have the same tangents at their zones of connection but different radii of curvature. The centers of these two circles are distant from each other on a straight line G which extends normal to the vertical central plane of the cylinder 3. The wall portions 12 are joined by a connecting piece 13 which is curved so as to extend in an arc of a circle having its center on the straight line H which extends in the vertical center plane of the cylinder 3, and which at the contacting places with the wall portions 12 has the same tangents. Due to this construction of the inside wall 5 of the cylinder 3 the chambers 9 and 9 in the section A have the same cubic contents. The effective part a of the sliding pistons 7 is constant Within the section A, for the sliding pistons '7 within this section do not vary their positions in the slots 6. in the middle of the section A the wall of the cylinder 3 is provided with a narrow slot Li placing the Working space 8 in communication with the atmosphere. The secondary suction a -sorption is through this slot 14. The housing 2 of the machine 1 rests on a base 15.

The machine operates as follows:

Owing to the rotation of the piston drum 4 in the direction of the arrow the air from the chamber 8 connected to the suction chamber it is evacuated. This process is finished when the sliding piston '7" has reached a controlling edge 16 in the suction chamber lil. On continued rotation of the piston drum 4 the slidin piston 7 opens slot 14 of the secondary suction adsorption, in consequence of which atmospheric air is drawn into the evacuated chamber 9" and fills it. The secondary suction adsorption is terminated by the rotary motion of the piston drum 4 as soon as the sliding piston 7" has passed the slot 14. Now compression of the air enclosed in the chamber 9" gets started. When the sliding piston 7 has reached a controlling edge 17 in the pressure chamber 11, the compressed air is dicharged to the compressed-air extraction place via the pressure chamber 11.

The disadvantage that part of the air sucked in by the secondary suction adsorption is pressed again to the outside through the slot 14 will not set in because the chambers 9 and 9" have the same cubic contents, so thatthere is no reduction in the cubic contents of the chamber in the section A on rotation of the piston drum 4. Because the sliding pistons 7 within the range of the section A will also not get displaced there will neither be any jamming. Owing to the construction of the wall portion 12 which forms the inside wall 5 of the cylinder 3 within the range of the suction side as far as the controlling edge 16 of the suction chamber 10, the primary suction adsorption will fully deliver its volume of air, as is the case with vacuum pumps without secondary suction adsorption.

The invention can also be used for multicell machines with dry-rotating piston drums, without having any noticeable reduction of compressed air.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

We claim:

1. In a vane pump operating as pressure and vacuum pump, in combination, a cylinder having an inner peripheral surface and opposite closed ends; a circular cylindrical drum turnable in one direction about its axis and arranged in said cylinder eccentrically with respect thereto so as to form between said inner surface of said cylinder and the outer surface of said drum an arcuate Working space, said drum being formed with a plurality of slots angularly spaced from each other and extending through the whole length of said drum; a suction chamher and a pressure chamber respectively communicating with the interior of said cylinder in the region of opposite ends of said arcuate working space; a sliding vane in each slot and having an outer edge engaging said inner peripheral surface of said cylinder so as to divide said arcuate working space into a plurality of chambers, said arcuate working space extending over an angle greater than that enclosed by three adjacent vanes and the inner peripheral surface of said sylinder having at the region of the apex of said Working space a circular cylindrical surface portion having an axis coinciding with the axis of said drum and said circular cylindrical surface portion extending from said suction chamber through an angle greater than that enclosed by three adjacent vanes but being smaller than the angle over which said working space extends and the remainder of said inner peripheral surface of said cylinder having a surface portion approaching said drum in the direction of rotation of said drum so as to form a portion of said working space of decreasing volume; and an auxiliary suction opening providing communication between the atmosphere and said working space in the region thereof defined between said drum and said circular cylindrical surface portion of said cylinder, said suction chamber having a controlling edge at the inner surface of said cylinder trailing in direction of rotation of said drum and being spaced from said auxiliary suction opening through an angle greater than that included by two adjacent vanes and said pressure chamber having a controlling edge at the inner surface of said cylinder leading in direction of rotation of said drum and being angularly spaced from the leading end of said circular cylindrical surface portion through an angle at least substantially equal to that included by two adjacent vanes, whereby, when said suction chamber is connected to a space of subatmospheric pressure, air at atmospheric pressure will pass through said auxiliary suction opening into a chamber defined by two vanes respectively trailing and leading said auxiliary suction opening at any moment during rotation of said drum, which air will be prevented from passing into said suction chamber and which will be compressed in said portion of decreasing volume of said working space during further rotation of said drum before being discharged into said pressure chamber, and so that the amount and pressure of pressurized air furnished by the pump will be independent of the degree of vacuum in the space connected to said suction chamber.

2. A vane pump as set forth in claim 1, wherein said suction chamber communicates with the interior of said cylinder through a greater are than said pressure chamber.

3. In a vane pump operating as pressure and vacuum ump, in combination, a cylinder having an inner peripheral surface and opposite closed ends; a circular cylindrical drum turnable in one direction about its axis and arranged in said cylinder eccentrically with respect thereto so as to engage said inner peripheral surface of said cylinder substantially along a line so as to form between said inner surface of said cylinder and the outer surface of said drum an arcuate working space, said drum being formed with a plurality of slots angularly spaced through equal angles from each other and extending through the whole length of said drum; a suction chamher and a pressure chamber respectively communicating with the interior of said cylinder in the region of opposite ends of said arcuate Working space; a sliding vane in each slot and having an outer edge engaging said inner peripheral surface of said cylinder so as to divide said arcuate working space into a plurality of chambers, said arcuate Working space extending over an angle greater than that enclosed by three adjacent vanes and; the inner peripheral surface of said cylinder having at the region of the apex of said working space a circular cylindrical surface portion having an axis coinciding with the axis of said drum and said circular cylindrical surface portion extending from said suction chamber through an angle greater than that enclosed by three adjacent vanes but being smaller than the angle over which said working space extends and the remainder of said inner peripheral surface of said cylinder having a surface portion approaching said drum in the direction of rotation of said drum so as to form a portion of said working space of decreasing volume; an auxiliary suction opening arranged substantially diametrically opposite said line of contact between drum and cylinder and providing communication between the atmosphere and said working space in the region thereof defined btween said drum and said circular cylindrical surface portion of said cylinder, said suction chamber having a controlling edge at the inner surface of said cylinder trailing in direction of rotation of said drum and being spaced from said auxiliary suction opening through an angle greater than that included by two adjacent vanes and said pressure chamber having a controlling edge at the inner surface of said cylinder leading in direction of rotation of said drum and being angularly spaced from the leading end of said circular cylindrical surface portion through an angle at least substantially equal to that included by two adjacent vanes, whereby, when said suction chamber is connected to a space of subatmospheric pressure, air at atmospheric pressure will pass through said auxiliary suction opening into a chamber defined by two vanes respectively trailing and leading said auxiliary suction opening at any moment during rotation of said drum, which air will be prevented from passing into said suction chamber and which will be compressed in said portion of decreasing volume of said working space during further rotation of said drum before being discharged into said pressure chamber, and so that the amount and pressure of pressurized air furnished by the pump will be independent of the degree of vacuum in the space connected to said suction chamber.

4. In a vane pump operating as pressure and vacuum pump, in combination, a cylinder having an inner peripheral surface and opposite closed ends; a circular cylindrical drum turnable in one direction about its axis and arranged in said cylinder eccentrically with respect thereto so as to engage said inner peripheral surface of said cylinder substantially along a line so as to form between said inner surface of said cylinder and the outer surface of said drum an arcuate working space, said drum being formed with a plurality of slots angularly spaced through equal angles from each other and extending through the whole length of said drum; a suction chamber and a pressure chamber respectively communicating with the interior of said cylinder in the region of opposite ends of said arcuate working space; a sliding vane in each slot and having an outer edge engaging said inner peripheral surface of said cylinder so as to divide said arcuate Working space into a plurality of chambers, said arcua-te working space extending over an angle greater than that enclosed by three adjacent vanes and the inner peripheral surface of said cylinder having at the region of the apex of said arcuate working space a first circular cylindrical surface portion having an axis coinciding with the axis of said drum and said first circular cylindrical surface portion extending from said suction chamber through an angle greater than that enclosed by three adjacent vanes, but being smaller than the angle over which said working space extends and the remainder of said inner peripheral surface of said cylinder having a surface portion approaching said drum in the direction of rotation of said drum so as to form a portion of said working space of decreasing volume, a second circular cylindrical portion opposite said first portion and havan axis parallel to said axis of said drum and located in a common plane of symmetry of said first and second portions and passing through said line of contact between said cylinder and said drum, and a pair of third circular cylindrical portions joining said first and second portions and having at the ends thereof respectively joined to said first and second portions common tangents with said first and second portions, said third portions having axes parallel to said drum axis and located respectively at opposite sides of said plane of symmetry equally spaced therefrom in a plane normal to said plane of symmetry; and an auxiliary suction opening arranged substantially diametrically opposite said line of contact between drum and cylinder and providing communication between the atmosphere and said working space in the region thereof defined between said drum and said first circular cylindrical surface portion of said cylinder, said suction chamber having a controlling edge at the inner surface of said cylinder trailing in direction of rotation of said drum and being spaced from said auxiliary suc tion opening through an angle greater than that included by two adjacent vanes and said pressure chamber having a controlling edge at the inner surface of said cylinder leading in direction of rotation of said drum and being an ularly spaced from the leading end of said circular cylindrical surface portion through an angle at least substantially equal to that included by two adjacent vanes, whereby, when said suction chamber is connected to a space of subatmosperic pressure, air at atmospheric pressure will pass through said auxiliary suction opening into a chamber defined by two vanes respectively trailing and leading said auxiliary suction opening at any moment during rotation of said drum, which air will be prevented from passing into said suction chamber and which will be compressed in said portion of decreasing volume during further rotation of said drum before being discharged into said pressure chamber, and so that the amount and pressure of pressurized air furnished by the pump will be independent of the degree of vacuum in the space connected to said suction chamber.

References Cited by the Examiner UNITED STATES PATENTS 720,834 2/03 Michael 91121 1,237,668 8/17 Machlet 230152 1,804,604 5/31 Gilbert 103136 2,191,345 2/40 Gaede 230-47 2,523,317 9/50 McGill 230-152 2,639,855 5/53 Daniels 230--47 2,832,199 4/58 Adams et al. 103136 2,977,888 4/61 Livermore 1G3136 2,983,226 5/61 Liverrnore 103136 3,003,423 10/61 Drutchas 103--136 FOREIGN PATENTS 1,116,643 2/56 France.

433,488 8/35 Great Britain. 754,427 8/56 Great Britain.

KARL I. ALBRECHT, Primary Examiner.

JOSEPH H. BRANSON, In, Examiner. 

1. IN A VANE PUMP OPERATING AS PRESSURE AND VACCUUM PUMP, IN COMBINATION, A CYLINDER HAVING AN INNER PERIPHERAL SURFACE AND OPPOSITE CLOSED ENDS; A CIRCULAR CYLINDRICAL DRUM TURNAB LE IN ONE DIRECTION ABOUT ITS AXIS AND ARRANGED IN SAID CYLINDER ECCENTRICALLY WITH RESPECT THERETO SO AS TO FORM BETWEEN SAID INNER SURFACE OF SAID CYLINDER AND THE OUTER SURFACE OF SAID DRUM AN ARCUATE WORKING SPACE, SAID DRUM BEING FORMED WITH A PLURALITY OF SLOTS ANGULARLY SPACED FROM EACH OTHER AND EXTENDING THROUGH THE WHOLE LENGTH OF SAID DRUM; A SUCTION CHAMBER AND A PRESSURE CHAMBER RESPECCTIVELY COMMUNICATING WITH THE INTERIOR OF SAID CYLINDER IN THE REGION OF OPPOSITE ENDS OF SAID ARCUATE WORKING SPACE; A SLIDING VANE IN EACH SLOT AND HAVING AN OUTER EDGE ENGAGING SAID INNER PERIPHERAL SURFACE OF SAID CYLINDER SOA S TO DIVIDE SAID ARCUATE WORKING SPACE INTO A PLURALITY OF CHAMBERS, SAID ARCUATE WORKING SPACE EXTENDING OVER AN ANGLE GREATER THAN THAT ENCLOSED BY THREE ADJACENT VANES AND THE INNER PERIPHERAL SURFACE OF SAID SYLINDER HAVING AT THE REGION OF THE APEX OF SAID WORKING SPACE A CIRCULAR CYLINDRICAL SURFACE PORTION HAVING AN AXIS COINCIDING WITH THE AXIS OF SAID DRUM AND SAID CIRCULAR CYLINDRICAL SURFACE PORTION EXTENDING FROM SAID SUCTION CHAMBER THROUGH AN ANGLE GREATER THAN THAT ENCLOSED BY THREE ADJACENT VANES BUT BEING SMALLER THAN THE ANGLE OVER WHICH SAID WORKING SPACE EXTENDS THE REMAINDDER OF SAID INNER PERIPHERAL SURFACE OF SAID CYLINDRICAL HAVING A SURFACE PORTION APPROACHING SAID DRUM IN THE DIRECTION OF ROTATION OF SAID DRUM SO AS TO FORM A PORTION OF SAID WORKING SPACE OF DECREASING VOLUME; AND AN AUXILIARY SUCTION OPENING PROVIDING COMMUNICATION BETWEEN THE ATMOSPHERE AND SAID WORKING SPACE IN THE REGION THEREOF DEFINED BETWEEN SAID DRUM AND SAID CIRCULAR CYLINDRICAL SURFACE PORTION OF SAID CYLINDER, SAID SUCTION CHAMBER HAVING A CONTROLLING EDGE AT THE INNER SURFACE OF SAID CYLINDER TRAILING IN DIRECTION OF ROTATION OF SAID DRUM AND BEING SPACED FROM SAID AUXILIARY SUCTION OPENING THROUGHH AN ANGLE GREATER THAN THAT INCLUDED BY TWO ADJACENT VANES AND SAID PRESSURE CHAMBER HAVING A CONTROLLING EDGE AT THE INNER SURFACE OF SAID CYLINDER LEADING IN DIRECTION OF ROTATION OF SAID DRUM AND BEING ANGULARLY SPACED FROM THE LEADING END OF SAID CIRCULAR CYLIDRICAL SURFACE PORTION THROUGH AN ANGLE AT LEAST SUBSTANTIALLY EQUAL TO THAT INCLUDIED BY TWO ADJACENT VANES, WHEREBY, WHEN SAID SUCTION CHAMBER IS CONNECTED TO A SPACE OF SUBATMOSPHERIC PRESSURE, AIR AT ATMOSPHERIC PRESSURE WILL PASS THROUGH SAID AUXILIARY SUCTION OPENING INTO A CHAMBER DEFINED BY TWO VANES RESPECTIVELY TRAILING AND LEADING SAID AUXILIARY SUCTION OPENING AT ANY MOMENT DURING ROTATION OF SAID DRUM, WHICH AIR WILL BE PREVENTED FROM PASSING INTO SAID SUCTIONN CHAMBER AND WHICH WILL BE COMPRESSED IN SAID PORTION OF DECREASING VOLUME OF SAID WORKING SPACE DURING FURTHER ROTATION OF SAID DRUM BEFORE BEING DISCHHARGED INTO SAID PRESSURE CHAMBER, AND SO THAT THE AMOUNT AND PRESSURE OF PRESSUURIZED AIR FURNEISHED BY THE PUMP WILL BE INDEPENDENT OF THE DEGREE OF VACUUM IN THE SPACE CONNECTED TO SAID SUCTION CHAMBER. 